Although the idea of a "cougar" who dates much younger men has a certain cultural cachet, being a woman in your twenties who simply chooses a partner who's a bit younger is often viewed as weird, desperate, or deluded — basically, anything besides what it is, which is totally normal.
People have a much easier time, it seems, getting on board with the idea of a woman taking a younger partner for purely sexual reasons than they do with the idea of a woman in a serious relationship with a younger partner.
In an interview in Shape, psychotherapist Robi Ludwig claimed that, “In some cases, a younger guy is developmentally in a different place...he’s not ready for all of the pressures and responsibilities that go along with a committed relationship because his emotional maturity is not fully developed yet.”Again, this is generalizing that conflates age with a specific set of romantic values — plenty of people of all ages aren't interested in serious relationships, and plenty of people of all ages are interested in serious relationships, too.
Ludwig isn't necessarily describing a younger guy; instead, she's describing a guy who isn't interested in a serious relationship, a kind of dude who comes in all ages.
God knows that's what I felt, while dating the above-noted older dude — I felt like his desire for me marked me as more mature and interesting than my peers.